JP7437994B2 - Rubber composition and rubber molded article - Google Patents

Description

The present invention relates to a rubber composition and a rubber molded article, and more particularly to a rubber composition containing an ethylene/α-olefin/nonconjugated polyene copolymer rubber, and a rubber molded article made of a crosslinked product thereof.

Ethylene/α-olefin/nonconjugated polyene copolymers do not have unsaturated bonds in their main chains, so they have superior weather resistance, heat resistance, and ozone resistance compared to conjugated diene rubbers.
Rubber compositions containing ethylene/α-olefin/non-conjugated polyene copolymer rubber and crosslinked products thereof utilize the above-mentioned properties to be used in automobile industrial parts, industrial rubber products, electrical insulation materials, civil engineering and construction materials, rubber coatings, etc. Widely used in rubber products such as cloth. In particular, for seal parts used in dynamic environments, rubber products with excellent wear resistance are required, so it is widely known that carbon black is blended to improve reinforcing properties (Patent Documents 1 and 2). Such).

Further, Patent Documents 3 and 4 disclose a technique of blending carbon black surface-treated with an alkoxysilane compound or the like into a rubber component.

Japanese Patent Application Publication No. 2000-191863 JP2012-31342A Japanese Patent Application Publication No. 10-30067 Japanese Patent Application Publication No. 10-46047

However, in conventional rubber compositions containing carbon black, when reinforcing materials such as carbon black are added to increase the strength of the crosslinked product, processability deteriorates (viscosity increases when unvulcanized). In some cases, the flexibility of the crosslinked product may decrease.

Therefore, an object of the present invention is to provide a rubber composition that can produce a crosslinked product having excellent strength and flexibility while having processability comparable to that of conventional products.

The present inventors have discovered that the above-mentioned problems can be solved by blending carbon black that has been subjected to a specific surface treatment into a rubber composition, and have completed the present invention.
The gist of the present invention is as follows.

[1]
(A) Ethylene α- having a structural unit (a1) derived from ethylene, a structural unit (a2) derived from an α-olefin having 3 or more carbon atoms, and a structural unit (a3) derived from a non-conjugated polyene. A rubber composition comprising an olefin/nonconjugated polyene copolymer rubber and (B) carbon black surface-treated with an organohydrogenpolysiloxane compound.

[2]
The rubber composition of [1] above, wherein the non-conjugated polyene contains at least one selected from the group consisting of 5-ethylidene-2-norbornene (ENB) and 5-vinyl-2-norbornene (VNB).

[3]
The rubber composition of [1] or [2] above, wherein the α-olefin contains propylene.
[4]
The rubber composition according to any one of [1] to [3] above, wherein the content of the surface-treated carbon black (B) is 1 to 400 parts by mass based on 100 parts by mass of the copolymer rubber (A). thing.

[5]
The rubber composition according to any one of [1] to [4] above, further comprising a crosslinking agent.
[6]
A rubber molded article comprising a crosslinked product of the rubber composition of [5] above.

The rubber composition according to the present invention can produce a crosslinked product with excellent strength and flexibility while having processability comparable to that of conventional products.

Hereinafter, the rubber composition and the like according to the present invention will be explained in more detail.
[Rubber composition]
The rubber composition according to the present invention is
(A) Ethylene α- having a structural unit derived from ethylene (a1), a structural unit derived from an α-olefin having 3 or more carbon atoms (a2), and a structural unit derived from a non-conjugated polyene (a3) Olefin/non-conjugated polyene copolymer rubber (hereinafter also referred to as "copolymer rubber (A)"), and (B) carbon black surface-treated with an organohydrogenpolysiloxane compound (hereinafter referred to as "surface-treated carbon black"). (Also written as “(B)”)
It is characterized by including.

<Copolymer rubber (A)>
The ethylene/α-olefin/non-conjugated polyene copolymer rubber (A) has a structural unit (a1) derived from ethylene, a structural unit (a2) derived from an α-olefin having 3 or more carbon atoms, and a non-conjugated It has a structural unit (a3) derived from polyene.

The α-olefin has 3 or more carbon atoms, preferably 3 to 20 carbon atoms, and more preferably 3 to 8 carbon atoms.
Examples of the α-olefin include propylene, 1-butene, 4-methylpentene-1, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 1-undecene, 1-dodecene, 1-tridecene, 1-tetradecene, 1-pentadecene, 1-hexadecene, 1-heptadecene, 1-nonadecene, 1-eicosene, 9-methyldecene-1, 11-methyldodecene-1 and 12-ethyltetradecene-1. . Among these, propylene, 1-butene, 4-methylpentene-1, 1-hexene and 1-octene are preferred, and propylene is particularly preferred.

These α-olefins may be used alone or in combination of two or more.
Examples of the non-conjugated polyene include:
1,4-hexadiene, 3-methyl-1,4-hexadiene, 4-methyl-1,4-hexadiene, 5-methyl-1,4-hexadiene, 4,5-dimethyl-1,4-hexadiene, 7- linear nonconjugated dienes such as methyl-1,6-octadiene, 8-methyl-4-ethylidene-1,7-nonadiene and 4-ethylidene-1,7-undecadiene;
Methyltetrahydroindene, 5-ethylidene-2-norbornene (ENB), 5-methylene-2-norbornene, 5-isopropylidene-2-norbornene, 5-vinylidene-2-norbornene, 6-chloromethyl-5-isopropenyl- Cyclic non-conjugated dienes such as 2-norbornene, 5-vinyl-2-norbornene (VNB), 5-isopropenyl-2-norbornene, 5-isobutenyl-2-norbornene, cyclopentadiene and norbornadiene;
2,3-diisopropylidene-5-norbornene, 2-ethylidene-3-isopropylidene-5-norbornene, 2-propenyl-2,2-norbornadiene, 4-ethylidene-8-methyl-1,7-nonadiene, etc. Examples include triene. Among these, 5-ethylidene-2-norbornene and 5-vinyl-2-norbornene are preferred.

These non-conjugated polyenes may be used alone or in combination of two or more.
The molar ratio ((a1)/(a2)) of the structural unit (a1) derived from ethylene and the structural unit (a2) derived from α-olefin is preferably 50/50 to 95/5, more preferably Preferably it is 60/40 to 80/20.

The proportion of the structural unit (a3) derived from a non-conjugated polyene in the copolymer rubber (A) is preferably 1.0 to 20.0% by mass, more preferably 3.0 to 15% by mass, More preferably, it is 4.0 to 14% by mass.

The intrinsic viscosity [η] of the copolymer rubber (A) measured in decalin at 135° C. is usually 0.5 to 5.0 dL/g, preferably 0.5 to 4.0 dL/g. .
Examples of the copolymer rubber (A) include ethylene/propylene/5-ethylidene-2-norbornene random copolymer, and ethylene/propylene/5-ethylidene-2-norbornene/5-vinyl-2-norbornene random copolymer. Examples include copolymers.

The method for producing the copolymer rubber (A) is not particularly limited, and for example, the method described in [0012] to [0018] of Patent Document 1 (Japanese Unexamined Patent Publication No. 2012-31342) can be adopted.

<Surface treated carbon black (B)>
The surface-treated carbon black (B) is carbon black that has been surface-treated with an organohydrogenpolysiloxane compound. Examples of the carbon black to be surface-treated include various carbon blacks such as SAF, ISAF, HAF, MAF, FEF, GPF, SRF, FT, and MT.

The average particle size of the surface-treated carbon black (B) and the surface-treated carbon black is preferably 20 to 50 μm, more preferably 20 to 40 μm, from the viewpoint of reinforcing properties and processability of the rubber composition.

Examples of the organohydrogenpolysiloxane compounds include compounds represented by the following general formula (1).

In formula (1), a plurality of R's are each independently a hydrocarbon group having 1 to 20 carbon atoms or a cyano group-containing group, preferably a hydrocarbon group having 1 to 15 carbon atoms, and more preferably a hydrocarbon group having 1 to 15 carbon atoms. It is an alkyl group having 1 to 10 carbon atoms.

Examples of R include methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, t-butyl group, pentyl group, hexyl group, octyl group, cycloalkyl group, phenyl group, cyano group, vinyl group. , allyl group.

m is an integer from 1 to 50, preferably from 2 to 30.
n is an integer from 1 to 50, preferably from 2 to 30.
Examples of the compound represented by the general formula (1) include ethylhydrogenpolysiloxane, propylhydrogenpolysiloxane, and methylhydrogenpolysiloxane (compounds in which all R's are methyl groups in the general formula (1)). preferable.

The surface treatment of carbon black with an organohydrogenpolysiloxane compound can be performed by a conventionally known method.
An example of a commercially available surface-treated carbon black (B) is "SI01-4 DK" (manufactured by Daito Kasei Co., Ltd.).

The amount of the surface-treated carbon black (B) in the rubber composition according to the present invention is determined from the viewpoint of the balance between physical properties (strength and flexibility of the crosslinked product) and roll processability, to the extent that the copolymer rubber (A) It is preferably 1 to 400 parts by weight, more preferably 10 to 150 parts by weight, and even more preferably 50 to 100 parts by weight.

Carbon black usually has carboxyl groups, hydroxyl groups, etc. on its surface, so when it is blended with EPDM, it has poor compatibility with EPDM and aggregation of the carbon blacks is observed. On the other hand, since the surface-treated carbon black (B) has a group represented by R in the above formula (1), it has high compatibility with EPDM, is well dispersed in the EPDM composition, and Since the Si-O bonds of the organohydrogenpolysiloxane compound have high bond energy, the rubber composition of the present invention containing the surface-treated carbon black (B) has the same processability as conventional products (for example, It is speculated that it is possible to produce a crosslinked product that has excellent strength and flexibility while having a vulcanized rubber composition (evaluated by the Mooney viscosity of the rubber composition).

<Reinforcement material>
The surface-treated carbon black (B) also functions as a reinforcing material for the copolymer rubber (A) in the rubber composition according to the present invention, but the rubber composition according to the present invention does not have the effects of the present invention. A reinforcing material other than the surface-treated carbon black (B) may be included as long as it does not impair it.

Examples of such reinforcing materials include reinforcing materials commonly used as reinforcing materials for synthetic rubber. Specific examples include silica, activated calcium carbonate, light calcium carbonate, heavy calcium carbonate, finely divided talc, finely divided silicic acid, talc and clay, those whose surfaces have been treated with a silane coupling agent, etc., and those which have not been surface treated. carbon black, and surface-treated carbon black (excluding the surface-treated carbon black (B)).

These may be used alone or in combination of two or more.
When the reinforcing material is used, the amount of the reinforcing material in the rubber composition according to the present invention is the total amount of the reinforcing material and the surface-treated carbon black (B), and the amount of the reinforcing material is equal to the amount of the copolymer rubber (A). The amount is usually 10 to 800 parts by weight, preferably 20 to 300 parts by weight per 100 parts by weight.

<Crosslinking agent>
The rubber composition according to the present invention may contain a crosslinking agent.
Examples of the crosslinking agent include vulcanizing agents such as sulfur, sulfur compounds, and organic peroxides.

(vulcanizing agent)
Examples of vulcanizing agents include sulfur and sulfur compounds.
Examples of sulfur include powdered sulfur, precipitated sulfur, colloidal sulfur, surface treated sulfur, and insoluble sulfur. Sulfur also functions as a crosslinking aid when an organic peroxide described below is used.

Examples of sulfur compounds include sulfur chloride, sulfur dichloride, polymeric polysulfides, and sulfur compounds that release active sulfur at the vulcanization temperature to vulcanize (e.g., morpholine disulfide, alkylphenol disulfide, tetramethyl thiuram disulfide, dipentamethylenethiuram tetrasulfide, selenium dimethyldithiocarbamate).

Among these, sulfur is preferred.
These may be used alone or in combination of two or more.
When the vulcanizing agent is used, the amount of the vulcanizing agent in the rubber composition according to the present invention is usually 0.1 to 10 parts by mass, based on 100 parts by mass of the copolymer rubber (A). Preferably it is 0.3 to 5 parts by mass.

(vulcanization accelerator)
It is preferable to use a vulcanization accelerator in combination with the vulcanizing agent.
Examples of the vulcanization accelerator include:
Sulfenamide compounds such as N-cyclohexyl-2-benzothiazolesulfenamide, N-oxydiethylene-2-benzothiazolesulfenamide, N,N-diisopropyl-2-benzothiazolesulfenamide;
2-mercaptobenzothiazole (e.g. Suncella M (trade name, manufactured by Sanshin Kagaku Kogyo Co., Ltd.)), 2-(2',4'-dinitrophenyl)mercaptobenzothiazole, 2-(morpholinodithio)benzothiazole ( Examples: Thiazole compounds such as Noxeler MDB-P (trade name, manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd.), dibenzothiazyl disulfide (e.g. Sunseler DM);
Guanidine compounds such as diphenylguanidine, diorthotolylguanidine, diorsonitrileguanidine, orsonitrile biguanide, diphenylguanidine phthalate;
Aldehyde amines or aldehyde-ammonia compounds such as acetaldehyde-aniline reactants, butyraldehyde-aniline condensates, hexamethylenetetramine, acetaldehyde ammonia;
Imidazoline compounds such as 2-mercaptoimidazoline;
Thiourea-based compounds such as thiocarbanilide, diethylthiourea, N,N'-dibutylthiourea (for example, Sancera BUR), trimethylthiourea, diorthotolylthiourea;
Tetramethylthiuram monosulfide (e.g. Suncella TS), tetramethylthiuram disulfide (e.g. Suncella TT), tetraethylthiuram disulfide (e.g. Suncella TET), tetrabutylthiuram disulfide (e.g. Suncella TBT), dipentamethylenethiuram tetrasulfide Thiuram compounds such as (for example, Suncella TRA);
Zinc dimethyldithiocarbamate (e.g. Suncella PZT), zinc diethyldithiocarbamate (e.g. Suncella EZT), zinc lead dibutyldithiocarbamate (e.g. Suncella BT), zinc ethylphenyldithiocarbamate, zinc butylphenyldithiocarbamate, sodium dimethyldithiocarbamate. , dithioate salt compounds such as selenium dimethyldithiocarbamate and tellurium dimethyldithiocarbamate;
Xanthate compounds such as zinc dibutylxanthate;
Zinc white (zinc oxide)
("Suncellar" is a trade name of a vulcanization accelerator manufactured by Sanshin Kagaku Kogyo Co., Ltd.). These may be used alone or in combination of two or more.

When the vulcanization accelerator is used, the amount of the vulcanization accelerator in the rubber composition according to the present invention is usually 0.1 to 20 parts by mass based on 100 parts by mass of the copolymer rubber (A). parts, preferably 0.2 to 10 parts by weight.

(organic peroxide)
Examples of the organic peroxides include dicumyl peroxide, di-t-butyl peroxide, di-t-butylperoxy-3,3,5-trimethylcyclohexane, t-butyl hydroperoxide, t-butyl cumyl peroxide, benzoyl peroxide, 2,5-dimethyl-2,5-di(t-butylperoxine)hexine-3, 2,5-dimethyl-2,5-di(benzoylperoxy)hexane, 2, Examples include 5-dimethyl-2,5-mono(t-butylperoxy)-hexane and α,α'-bis(t-butylperoxy-m-isopropyl)benzene. Among these, dicumyl peroxide, di-t-butyl peroxide, and di-t-butylperoxy-3,3,5-trimethylcyclohexane are preferred. These may be used alone or in combination of two or more.

When the organic peroxide is used, the amount of the organic peroxide in the rubber composition according to the present invention is usually 0.0003 to 0.05 mol per 100 g of the copolymer rubber (A). Preferably it is 0.001 to 0.03 mol.

(Crosslinking aid)
It is preferable to use a crosslinking aid together with the organic peroxide.
Examples of the crosslinking aid include quinone dioxime compounds such as p-quinone dioxime, methacrylate compounds such as polyethylene glycol dimethacrylate, allyl compounds such as diallyl phthalate and triallyl cyanurate, maleimide compounds, and divinyl. Examples include benzene. These may be used alone or in combination of two or more.

When the crosslinking aid is used, the amount of the crosslinking aid in the rubber composition of the present invention is 0.5 to 2 mol, preferably approximately equal to 1 mol of the organic peroxide used. It is a mole.

<Softener>
The rubber composition according to the present invention may contain a softener.
As the softener, a softener commonly added to rubber compositions can be used.

Examples of the softening agent include:
Process oils, lubricating oils, paraffin, liquid paraffin, petroleum asphalt, petroleum softeners such as petrolatum;
Coal tar-based softeners such as coal tar and coal tar pitch;
Fatty oil-based softeners such as castor oil, linseed oil, rapeseed oil, coconut oil;
Tall oil;
sub;
Waxes such as beeswax, carnauba wax, lanolin;
Fatty acids and fatty acid salts such as ricinoleic acid, palmitic acid, barium stearate, calcium stearate, zinc laurate;
Examples include synthetic polymeric substances such as petroleum resin, atactic polypropylene, and coumaron indene resin. Among these, petroleum-based softeners are preferred, and process oils are particularly preferred. These may be used alone or in combination of two or more.

When the softener is used, the amount of the softener in the rubber composition according to the present invention is usually 150 parts by weight or less, preferably 130 parts by weight, based on 100 parts by weight of the copolymer rubber (A). It is as follows.

<Processing aid>
The rubber composition according to the present invention may contain a processing aid.
As the processing aid, processing aids that are commonly blended into rubber compositions can be used.

Examples of the processing aids include:
Higher fatty acids such as goricinoleic acid, stearic acid, palmitic acid, and lauric acid;
Higher fatty acid salts such as barium stearate, zinc stearate, calcium stearate;
Examples include higher fatty acid esters such as ricinoleic acid ester, stearic acid ester, palmitic acid ester, and lauric acid ester. These may be used alone or in combination of two or more.

When the processing aid is used, the amount of the processing aid in the rubber composition according to the present invention is usually 10 parts by mass or less, preferably 5 parts by mass, based on 100 parts by mass of the copolymer rubber (A). Parts by mass or less.

<Other ingredients>
In addition to the above-mentioned components, the rubber composition according to the present invention may include various known compounding agents generally used in the manufacture of rubber products, such as aging Inhibitors, activators, reaction inhibitors, colorants, dispersants, flame retardants, plasticizers, antioxidants, scorch inhibitors, ultraviolet absorbers, antistatic agents, lubricants, fungicides, mastication accelerators, adhesives Additives, dyes (disperse dyes, acid dyes, etc.), inorganic/organic pigments, surfactants, foaming agents (foaming agents, foaming aids, etc.), or defoaming agents may be used in a manner that would impair the purpose of the present invention. It may be selected as appropriate within the range and may be blended in an appropriate amount.

(Method for producing rubber composition)
The rubber composition according to the present invention can be produced by a conventionally known production method for rubber compositions, except for using the copolymer rubber (A) and the surface-treated carbon black (B) as raw materials. Can be done.

As a method for producing the rubber composition according to the present invention, the copolymer rubber (A), the surface-treated carbon, Black (B) and, if necessary, a reinforcing material, a softener (for oil extension), a processing aid, a vulcanization accelerator, etc. are kneaded at a temperature of 80 to 170°C for 2 to 20 minutes. Next, additives such as a softening agent, a vulcanizing agent (for example, sulfur), a vulcanization accelerator, and, if necessary, a blowing agent and a crosslinking agent are added to the obtained blend by rolls such as open rolls, Alternatively, use a kneader to additionally mix a vulcanization accelerator, crosslinking aid, foaming aid, and removal agent as necessary, knead at a roll temperature of 40 to 80°C for 5 to 30 minutes, and then dispense. It can be manufactured by

[Rubber molded body]
The rubber molded article according to the present invention is made of a crosslinked product (vulcanized product) of the rubber composition according to the present invention, and has excellent sliding properties. Therefore, it can be used for a variety of purposes including automobile parts, home appliance-related parts, civil engineering/building material-related parts, miscellaneous goods, and daily necessities.

Examples of such uses include:
Automotive and aircraft weatherstrips (e.g. door weatherstrips, trunk weatherstrips, luggage weatherstrips, roof side rail weatherstrips, sliding door weatherstrips, ventilator weatherstrips, sliding loop panel weatherstrips, front window weatherstrips, rear window weatherstrips) strip, quarter window weatherstrip, lock pillar weatherstrip, door glass outer weatherstrip, door glass inner weatherstrip),
Dam windshield, glass run channel, door mirror bracket, seal headlamp, seal cowl top;
Automotive hoses (e.g. brake hoses, radiator hoses, heater hoses, air cleaner hoses, water supply hoses),
gas hose,
Building material sealing parts (e.g. gaskets, airtight, joint materials)
doorstop,
home appliance seal parts,
Automotive cup sealing materials (e.g. master cylinder piston cup, wheel cylinder piston cup),
Examples include sealing materials for industrial machines, sheets, transmission belts or conveyor belts, coated wires, wire joints, electrical insulation parts, semiconductive rubber parts, rolls for OA equipment, rolls for industrial use, rubber products for household use, and shoes.

The rubber molded article of the present invention may be a foamed molded article as long as the effects of the present invention are not impaired. Examples of foam molded products include highly foamed sponge materials such as weather strip sponge materials such as door sponges, opening trim sponges, hood seal sponges, and trunk seal sponges, insulation sponges, and dam rubber.

(Method for producing rubber molded body)
The rubber molded article according to the present invention can be obtained by preparing an unvulcanized rubber composition according to the present invention in the manner described above, in the same way as when general rubber is vulcanized (crosslinked), and then (or At the same time, it can be manufactured by molding into a desired shape and then vulcanizing (crosslinking).

The unvulcanized rubber composition according to the present invention prepared as described above can be molded and vulcanized by various molding methods, preferably by molding such as compression molding, injection molding, and injection molding. Can be molded and vulcanized.

In the case of compression molding, for example, a pre-weighed unvulcanized rubber composition according to the present invention is placed in a mold, the mold is closed, and then heated at a temperature of 120 to 270°C for 30 seconds to 120 minutes to achieve the desired purpose. A vulcanized rubber molded body is obtained.

In the case of injection molding, for example, a preset amount of ribbon-shaped or pellet-shaped compounded rubber is fed into a pot by a screw, and then preheated compounded rubber is fed into the mold by a plunger in 1 to 20 seconds. After the compounded rubber is injected, it is heated at a temperature of 120 to 270°C for 30 seconds to 120 minutes to obtain the desired rubber molded body.

In the case of injection molding, for example, a pre-weighed compounded rubber is placed in a pot and injected into the mold using a piston for 1 to 20 seconds, and after the compounded rubber is injected, it is heated at a temperature of 120 to 270°C for 30 seconds to 120 minutes. By doing so, the desired vulcanized rubber molded body can be obtained.

EXAMPLES The present invention will be explained below with reference to Examples, but the present invention is not limited to these Examples.
[Unvulcanized rubber properties]
<Mooney viscosity>
The Mooney viscosity ML (1+4) 100° C. of the unvulcanized rubber was measured using a Mooney viscometer (SMV202 model manufactured by Shimadzu Corporation) in accordance with JIS K6300.

[Vulcanized rubber properties]
<Hardness>
The hardness (type A durometer hardness) of the sheet was measured in accordance with JIS K6253. However, six rubber sheets each having a thickness of 2 mm were stacked on top of each other to have a thickness of approximately 12 mm, which was used as a test piece. No test pieces with foreign matter, bubbles, or scratches were used. In addition, the dimensions of the measurement surface of the test piece were such that measurements could be made at a position where the indenter tip was 12 mm or more away from the end of the test piece.

<Tensile properties>
In accordance with JIS K6251, a tensile test was conducted at a measurement temperature of 23°C and a tensile speed of 500 mm/min to measure the tensile strength at break (T _b ) [MPa] and elongation at break (E _b ) [%] of the rubber sheet. did.

[Comparative example 1]
100 parts by mass of ethylene/propylene/5-ethylidene-2-norbornene ternary copolymer (trade name: Mitsui EPT 4045M, manufactured by Mitsui Chemicals, Inc.), 1 part by mass of stearic acid, 5 parts by mass of zinc white, 80 parts by mass of carbon black (FEF) (product name: Asahi #60UG, manufactured by Asahi Carbon Co., Ltd., physical properties are as listed in Table 1), and paraffinic process oil (product name: Diana Process PW-380, (manufactured by Idemitsu Kosan Co., Ltd.) and kneaded for 5 minutes using a 1.7 liter Banbury mixer.

Furthermore, after this compound was wound around a 6-inch roll with a surface temperature of 50°C, a vulcanization accelerator (trade name: Suncellar M, manufactured by Sanshin Kagaku Kogyo Co., Ltd.) was added to 236 parts by mass of this compound. 0.5 parts by mass, 1 part by mass of a vulcanization accelerator (trade name: Suncella TT, manufactured by Sanshin Kagaku Kogyo Co., Ltd.), and 1.5 parts by mass of sulfur were added and kneaded for 8 minutes to obtain a blend. I let things cool.

From this compound (unvulcanized rubber composition), vulcanization was performed at 160° C. for 20 minutes using a press molding machine to prepare a rubber sheet (vulcanized rubber) with a thickness of 2 mm.
Various physical properties of the compound (unvulcanized rubber) and rubber sheet (vulcanized rubber) obtained as described above were measured by the above method. The results are shown in Table 2.

[Example 1]
Carbon black (FEF) was changed to 80 parts by mass of carbon black surface-treated with methylhydrogenpolysiloxane (product name: SI01-4 DK, manufactured by Daito Kasei Co., Ltd., physical properties are as listed in Table 1). A compound (unvulcanized rubber) and then a rubber sheet (vulcanized product) were prepared in the same manner as in Comparative Example 1 except for the above.

Various physical properties of the compound (unvulcanized rubber) and rubber sheet (vulcanized rubber) obtained as described above were measured by the above method. The results are shown in Table 2.

Claims (5)

(A) Ethylene α- having a structural unit (a1) derived from ethylene, a structural unit (a2) derived from an α-olefin having 3 or more carbon atoms, and a structural unit (a3) derived from a non-conjugated polyene. Contains olefin/non-conjugated polyene copolymer rubber and (B) carbon black surface-treated with an organohydrogenpolysiloxane compound,
The content of the surface-treated carbon black (B) is 1 to 400 parts by mass based on 100 parts by mass of the copolymer rubber (A).
Rubber composition. The rubber composition according to claim 1, wherein the non-conjugated polyene contains at least one selected from the group consisting of 5-ethylidene-2-norbornene and 5-vinyl-2-norbornene. The rubber composition according to claim 1 or 2, wherein the α-olefin contains propylene. The rubber composition according to any one of claims 1 to 3 , further comprising a crosslinking agent. A rubber molded article comprising a crosslinked product of the rubber composition according to claim 4 .